The present invention pertains generally to the field of pipe couplers, and is particularly adapted to the field of couplers for use in well drilling operations.
In such operations, the rotary drilling force is applied through the pipe itself, and this requires that the couplers use between adjacent lengths of pipe be capable of withstanding the considerable torque loads applied. At the same time, the outside diameter of the coupling must be kept to a minimum addition over the diameter of the pipe itself, so as to avoid undue restrictions when lowering the pipe into the drill hole. However, the internal dimensions of the fluid passageway must be kept as close to the internal dimensions of the pipe itself, so as to avoid introducing undue restrictions in terms of the pumping of fluid through the pipes and couplers.
It is also necessary that the coupler be simple and efficient in engagement and locking, so that the drilling process will not be impeded by the amount of time required to adjoin lengths of pipe.
The above requirements for pipe couplers impose severe, and sometimes contradictory, constraints upon the design of a coupler system, and although numerous prior art systems have been proposed and have achieved workable results, there has always been room for further improvement in terms of size, efficiency and cost.